version: include tag commit date for easy reference
version: include tag commit date for easy reference

This is more for users trying to get a sense of how old/new their
current version of repo is when debugging issues.

Change-Id: Ifb413c679bb8c8dbf4f9334137adf086bb000a68
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/261192
Reviewed-by: Jonathan Nieder <96e93edf89a1b75e35c5d08e01778cfc4fff73d9@google.com>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@google.com>

aosp-mirror/tools_repo,lewixliu/git-repo,couchbasedeps/git-repo,codetutil/git-repo,couchbasedeps/git-repo,aosp-mirror/tools_repo,codetutil/git-repo,lewixliu/git-repo,TheQtCompany/git-repo,lipro-yocto/git-repo,mer-tools/git-repo,GerritCodeReview/git-repo,lipro-yocto/git-repo,GerritCodeReview/git-repo,TheQtCompany/git-repo,mer-tools/git-repo